Answer:
1.Our energy supply comes mainly from fossil fuels, with nuclear power and renewable sources rounding out the mix. These sources originate mostly in our local star, the Sun.
2.Machines can be simple, like a lever or pulley, or they can be more complex, like a computer or an automobile. The main purpose of a machine is to make things easier for people, like lifting and moving heavy objects around, working out a mathematical equation or even ordering food from a restaurant.
3.A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. ... Early computers were only conceived as calculating devices
